Utilization of indeterministic block cipher Use of an asymmetric block cipher results in Length of the units of encryption Error extension only within the block (assuming the borders of blocks are preserved) Qualified also for authentication? Properties of the operation modes ECB CBC PCBC CFB OFB OCFB + possible - impossible + asymmetric stream cipher - symmetric stream cipher - determined by block length of the block cipher yes, if redundancy within every block 2 blocks (assuming the borders of blocks are preserved) yes, if deterministic block cipher potentially unlimited yes, even concealment in the same pass 1 + �b/r� blocks, if error placed rightmost, else possibly one block less yes, if deterministic block cipher + user-defined none as long as no bits are lost or added yes, if adequate redundancy potentially unlimited yes, even concealment in the same pass 247